Conditions and treatments
Patellar Dislocation
Patellofemoral joint
We can straighten the leg thanks to the action of a thigh muscle called quadriceps. This muscle is not connected directly to the leg. There is a bone that bridges two tendons related to the quadriceps: the patella. The quadriceps is connected to it through the quadriceps tendon, and the “bridge” is completed by another one called patellar tendon. As the leg bends and straightens, the patella is stabilised by ligaments and engages a groove from the thigh bone (femur) called trochlea.
What causes a patellar dislocation?
It occurs when the patella moves out of the femoral groove (trochlea). This can happen due to a direct impact (traumatic), or just by suddenly changing direction or pivoting. The latter may happen due to predisposing factors related to the muscle-skeletal anatomy of the lower limb.
What are the symptoms and how is it diagnosed?
When a dislocation happens a deformity is seen as the patella pops out of the groove and stands outside of the knee. Sometimes the patella stays displaced and needs to be pushed back to its place, others it jumps back in by itself. What follows is pain, swelling and difficulty in weight-bearing. Symptoms will subside with time, but depending on the damage to the knee, anatomy, and if there was loss of the knee cap stabilisers, further episodes of patella dislocation may occur, or a feeling of “almost popping out” may be described. In the acute setting, the diagnosis is made by visualising the deformity, or by the episode described by the patient. Imaging investigation with X-rays, CT scan or MRI may be needed to understand if there was a fracture or other extensive damage that may need urgent care.
How is it treated?
According to most current evidence, the first episode should be treated without surgery, except in special situations like fractures. Pain management, icing, weight-bearing as tolerated with the help of crutches is indicated. A brace may help with pain, rest and healing of structures. After this initial period, a rehabilitation programme will help getting back the range of motion and strengthening thigh and hip muscles. This will lower the chances of a new dislocation, and get the person back to daily life activities/sports. Nevertheless, it is important to understand the mechanism of injury, and analyse if there are risk factors predisposing new episodes. Where recurrent dislocation develops, surgery may be indicated to provide stability to the patella, lowering the risk of further damage to the articular cartilage, and improving function. The procedures vary according to the anatomical changes that are identified: reconstruction of ligaments, or realigning the patella through procedures in the bone. After surgery, you will use crutches for a few weeks, take medications to control pain and swelling, and start a rehabilitation programme which will help you returning to your sports activities at the earliest time possible.
